Constant array slice size check.

Cython/Compiler/Nodes.py

@@ -4819,7 +4819,23 @@ class SingleAssignmentNode(AssignmentNode):
                 step_node = None #self.rhs.step
                 if step_node:
                     step_node = step_node.coerce_to(PyrexTypes.c_py_ssize_t_type, env)
-                # TODO: check (stop - start) / slice
+                # TODO: Factor out SliceIndexNode.generate_slice_guard_code() for use here.
+                def get_const(node, none_value):
+                    if node is None:
+                        return none_value
+                    elif node.has_constant_result:
+                        node.calculate_constant_result()
+                        return node.constant_result
+                    else:
+                        raise ValueError, "Not a constant."
+                try:
+                    slice_size = (get_const(stop_node, None) - get_const(start_node, 0)) / get_const(step_node, 1)
+                    if target_size != slice_size:
+                        error(self.pos, "Assignment to/from slice of wrong length, expected %d, got %d" % (
+                                slice_size, target_size))
+                except ValueError:
+                    error(self.pos, "C array assignment currently requires known endpoints")
+                    return
                 check_node = None
             else:
                 return